In the case of modern vehicles, in particular passenger carriages of railways, rapid transit railways or underground railways, it is endeavored for visual reasons and for practical reasons, to achieve an outer side wall surface which is as smooth as possible continuously and is also visually uniform. This leads, when the train enters the station, to the doors not being readily identifiable and therefore firstly to the doors not being released for exit by the waiting passengers and secondly the latter having to make a certain search effort to establish where the doors are located. Added to this is the fact that, in spite of platform illumination becoming ever better in recent years, the region of entry into the carriage itself, in particular in the case of swinging-sliding doors, is illuminated relatively poorly since both the lighting means from the platform and the lighting means from the interior of the train are only poorly able to cover this region simply for geometrical reasons. Added to this is also the fact that the people using the entry prevent the light, which generally comes obliquely from above, from the carriage or from the platform from reaching the ground region; that is, they pass through their own shadow.